On Mon, 2005-08-08 at 19:03 -0700, Ajay Sharma wrote:

Hi, This might sound like a n00b question, but I've honestly never done this with a Linux machine... (it is running Centos3)

It's not a noob question. It comes up regularly.

How would you do it?

I regularly do this on Linux and Solaris (and should be applicable to just about any other System-V UNIX flavor -- especially step #3) using the following procedure.

I recommend you do it from run-level 1 (or even init=/bin/sh), but it's not totally necessary (it all depends on what files are open and/or what is running).

1. Slice (partition) new disk and create new filesystems

NOTE: If you're using filesystem labels (e.g., e2label), we sure you enter them appropriate under #4 below. If you configure software RAID, remember your configuration files.

2. Create a new mount point, say /newroot, and mount new filesystem tree under /newroot

NOTE A: You do _not_ need a 1:1 filesystem setup, you can change your filesystem organization if you wish.

NOTE B: Also remember that /newroot/tmp, if a separate filesystem, should be chmod 1777, although #3 might correct this anyway.

3. Copy all existing data as follows ... (pretty much universal to all System-V UNIX flavors) ...

for i in / /fs1 /fs2 ...; do cd $i find . -mount | cpio -pmdv /newroot$i done

You can make this one line with: # for i in / /fs1 /fs2 ...; do cd $i; find . -mount | cpio - pmdv /newroot$i; done

NOTE A: The list of filesystems should be the _original_, not the new ones. Using the "-mount" (sometimes "-xdev" on other implementations) option to find does not cross filesystems, hence why you pass the existing filesystems. The new tree will be populated as appropriate.

NOTE B: "Sparse files" may be expanded after this operation and take up more disk space, depending on the filesystem(s) in use.

4. Modify filesystem (e.g., /newroot/etc/fstab), bootloader (e.g., /newroot/etc/grub.conf or lilo.conf), etc... as appropriate, including any LVM/MD disk organization.

6. Re-install bootloader (e.g., GRUB/LILO) to new disk

NOTE: You _may_ need to boot the distro's CD and recovery mode after you remove the former disk for proper BIOS-Linux device disk mapping. I've been able to do so in LILO without, but GRUB always seems to never likes the fact that my mappings don't line up until I make them actual (so I typically use the rescue CD).